Analysis of the Causation of Intense Rain in Pearl River Delta Long After Typhoon Nida(1604) Left

On the night of August 2,2016,a small-scale intense rain occurred in the region of Pearl River Delta,which was far from Typhoon Nida(1604) that had moved into Guangxi. With observations and reanalysis data from the ECMWF,we analyzed its causes and found that as Nida moved to the west,the subtropical high in the western Pacific also traveled westward and intensified so that an area of the southwesterly converging with the southeasterly was formed in the mid-and low-troposphere of Guangdong to provide favorable conditions of convergence and lifting for the rain in the delta. During the rain,there was sufficient amount of water vapor in the low level of southern China. Prior to the rain,circulation at the periphery of the typhoon transported dry air in the middle level of the atmosphere to the delta that superimposed with the lowlevel humid air. As a result,the psedo-equivalent geopotential temperature decreased remarkably with the fall of pressure,increasing the convective instability and thus confining the intense rain in the delta area and making it highly convective.